Status Light Indicators

During self-diagnostics, the status light display on ECC Panel is used to indicate switchable parameter status. Each different mode of operation is indicated by it's status light being turned ON or OFF. Status light indicators are relative to system level being tested (BCM or ECM). See Figure and Figure .

Following are brief summaries of each systems status light indicators, starting with the ECM status light indicators:

• HIGH indicator light will be ON when ECM is in closed loop fuel control. Light comes ON only after coolant and O2 sensors reach operating temperature.
• MED indicator light only indicates whether operation is enabled ON) or disabled (OFF) by ECM. Actual working operation depends on TCC system being in working order.
• LOW indicator light stays ON when oxygen sensor signals rich exhaust condition to ECM. Light will flash ON and OFF during warm engine, steady throttle, and proper fuel mix condition.
• LOWER ARROW indicator light will be ON when ECM is directing one of the 3 EGR solenoids to be ON. Light will be OFF if no EGR solenoids are ON as during idle condition.
• OFF indicator light will be ON when ECM senses 4th gear pressure switch open. Light should only be on in 4th gear.
• Left-side AUTO indicator light will be ON when ECM senses 3th gear pressure switch open. Light should only be on in 3rd or 4th gear.
• "°C" indicator light will be ON when ECM senses 2nd gear pressure switch open. Light should only be on in 2nd, 3rd or 4th gear.
• A/C Compressor Command LOWER ARROW indicator light will be ON only when ECM allows A/C clutch engagement through A/C relay. Light will also be ON if BCM requests ECM to turn clutch ON during test sequence. Light should be OFF if ECM commands disengagement.

Following are brief summaries of BCM system status light indicators:

• LOWER ARROW indicator light will be ON if BCM senses low refrigerant pressure switch is open. Light will remain OFF if A/C system is fully charged and operational. (However, light will come ON when outside vehicle ambient temperature is below -5°F (-21°C), this is due to temperature-pressure relationship of R-12 refrigerant.)
• OFF indicator light will be ON when BCM commands air recirculation.
• MED indicator light will be ON when BCM commands airflow out A/C vents. Light should also be ON in A/C and BI-LEV modes.
• LOW indicator light will be ON when BCM commands airflow out defroster outlets. Light should also be ON in defrost and A/C modes.
• HIGH indicator light will be ON when BCM commands airflow out floor outlets. Light should be ON in heater mode.
• Left-side AUTO indicator light will be ON when BCM requests ECM to engage A/C compressor clutch.